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Radio Science

A two-component rain model for the prediction of site diversity performance


  • Robert K. Crane,

  • Horng-Chung Shieh


A two-component rain attenuation model is presented for the prediction of single- and joint-(diversity) path rain attenuation statistics and for the prediction of the relative measures of diversity performance, diversity gain, and diversity improvement factor (or advantage). The model is based entirely on the use of geophysical parameters for the prediction of the effects of rain. It contains no free parameters to adjust to fit the available attenuation observations. The model is general and will handle both balanced and unbalanced diversity system design for terrestrial and satellite communication systems. Model performance was evaluated by comparison with published single-path and site diversity observations. The model performs well when tested against the International Radio Consultative Committee (CCIR) site diversity data base, providing predictions of the single-path attenuation values exceeded for specified percentages of a year with a root-mean-square difference (RMSD) from the observed values of 49% and providing predictions of the minimum attenuation value simultaneously exceeded on two links for specified percentages of a year with a RMSD of 59%.

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